For validation of Paxos and Accord 2 different consistency verifiers were created: accord.verify.StrictSerializabilityVerifier (Accord), and org.apache.cassandra.simulator.paxos.LinearizabilityValidator (Paxos). To increase confidence in both protocols it would be good to use an external consistency checker, such as Jepsen's Elle.
This work was first started in https://the-asf.slack.com/archives/C0459N9R5C6/p1692192925909199 by Jarek, and would be good to get as part of our automation. https://github.com/jepsen-io/elle/blob/main/LICENSE - Eclipse Public License 2.0